Through the years I have often checked various sources trying to understand what are "biologic therapies" but didn't get any general answer or generalized definition of the term.

Every medical treatment (possibly excluding psychotherapy) is "biological".
It may be a classic case were people try to describe something in too few words, similar to what goes with "Chemical Weapons". Every weapon (possibly excluding psychological warfare) is "chemical", but the term "Chemical Weapons" actually refers primarily to:

Bombs containing strong acids or poison

If I understand correctly, and I don't have a single source for this "biologic therapies" are in general:

Synthetic protein-agonists or synthetic protein-antagonists

A specific example would be TNF-α inhibitors in the treatment of psoriasis(1) but that's only a psoriasis-specific definition, so what are "biologic therapies" in general?

  • Think large molecules rather than small molecules.
    – Carey Gregory
    May 27, 2023 at 21:21
  • These are not well defined terms, or are they?
    – haidar
    May 30, 2023 at 8:54
  • I don't know that you'll find a formal definition, but it's a very common distinction in chemistry. Large molecule refers to proteins and other organic molecules often containing hundreds of atoms while small molecule refers to inorganic molecules such as found in most drugs.
    – Carey Gregory
    May 30, 2023 at 13:55

1 Answer 1


Wikipedia mentions that the definition varies by you who ask, and since there are some regulations that apply specifically to biologics you'd need to see those specific regulations to see how they apply, but generally my impression agrees with the general idea the Wikipedia article conveys: biologics are derived from biological sources.

Yes, all drugs affect biology, but most small molecules are created synthetically, even if they're motivated by things originally identified in living things. Large molecules like proteins (including antibodies), though, are only practical to make in biological systems.

  • Well, we could also say that medical cannabis "derives from biological sources". We could then say that a "biologic" is a a natural product of any organism whatsoever, in natural form or synthetic form, given as medicine but then, it's not very different than "purely synthetic medicine" anyway.
    – haidar
    May 27, 2023 at 23:26
  • Agreed, medical cannabis could be considered a biologic - it fits with all the added/distinct regulatory concerns that apply to biologics versus synthetic drugs, including being difficult to characterize (cannabis is going to have different concentrations of different molecules plant to plant). But if you change the rules and say "...or synthetic form" I'm losing you. That's not the definition, and if you want to change it to be something else, why bother asking?
    – Bryan Krause
    May 28, 2023 at 0:12
  • I don't try to change, but to understand. What the patient will get may not be a natural product isolated from an organism but a synthetic copy of it (created by chemical formula which was discovered from the natural product). Now do you understand me?
    – haidar
    May 28, 2023 at 0:48
  • @haidar If it's a synthetic copy, then it's not produced by a biological source so it's not a biologic.
    – Bryan Krause
    May 28, 2023 at 0:58
  • 1
    @haidar I assume they're all made in cell lines in vitro; that would be most common. Some things are still isolated from whole animals though.
    – Bryan Krause
    May 28, 2023 at 17:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.